The present invention relates to a system for selecting tools from a tool store of a machine tool for machining printed circuit boards.
Machine tools of the above type normally comprise a device for automatically exchanging tools between the tool store and the spindle of a corresponding machining head movable in a first direction or along an axis X. The store is normally fixed, and comprises a number of tools arranged in a row or in a matrix of rows and columns, and the tool-change device is fitted to the worktable.
Various types of systems for selecting tools from the store are known. In one known machine, the worktable is movable in two coordinate directions; the tool-change device comprises two grippers for respectively gripping the new tool and the used tool to be changed; and the tools are selected by moving the table in the two coordinate directions to align the tool-change device with the tool in the store and with the machining head. On account of the weight of the table, selecting and changing the tool take a fairly long time, thus increasing the running cost of the machine.
In another known machine tool, the machining head is fitted to a carriage movable along the X axis; the table is movable only along the Y axis; and the tool-change device comprises a first gripper fitted to the carriage to extract the new tool from the store and insert the used one, and a second gripper fitted to the table to extract the used tool from the spindle and insert the new one. This system, too, is fairly complicated and expensive.
Another known machine tool comprises a number of machining heads movable along a crosspiece parallel to the X axis, and a corresponding number of stores fitted to a slide, which is driven by a respective motor along the X axis to select the row in each store containing the required tool. The slide and the stores, however, clutter the front of the table, thus complicating loading and unloading of the boards on and off the table.